Mendel knew that the variations in the offspring

generations resulted from his experiments

because he

•A. allowed plants to cross-pollinate.

. b. ensured that plants self-pollinated.

. C. controlled the fertilization process.

. d. changed the growing conditions.

controlled the fertilization process.

Explanation:

Mendel took precautions to avoid contamination by pollen through self pollination of the P generation. He controlled the fertilization processes between the plants. He self pollinated the first pureline varieties to form the P generation. He then cross pollinated them to get F1 generation. Every step of his experiment was controlled.